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Short-term toxicity to fish

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Endpoint:
short-term toxicity to fish
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Refer to the analogue approach justification document provided in IUCLID section 13.
Reason / purpose:
read-across source
Related information:
Composition 1
Test material information:
Composition 1
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other:
Remarks:
Source: CAS 10023-48-0, Gado & Broschard, 2017
Conclusions:
The key value retained for the assessment of the short-term toxicity of the target substance to fish is the LC50 (96 h) > 100 mg/L (nominal, OECD 203, D. rerio, CAS 10023-48-0); read-across
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12 - 25 Apr 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Version / remarks:
adopted 17 Jul 1992
Qualifier:
according to
Guideline:
EU Method C.1 (Acute Toxicity for Fish)
GLP compliance:
yes (incl. certificate)
Remarks:
Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany (18 Nov 2014)
Test material information:
Composition 1
Analytical monitoring:
yes
Remarks:
HPLC-UV
Details on sampling:
- Concentrations: Control and 100 mg/L (limit concentration) at test start (0 h) and at test end (96 h).
- Sampling method: One replicate was given to an analytical laboratory for analysis. The second replicate was used as backup.
- Sample storage conditions before analysis: Deep frozen at ≤ - 20 °C. The stability of the test item during freezing was demonstrated in a separate non-GLP study.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution with 100 mg/L test item in reconstituted water was prepared and stirred for 30 min with a magnetic stirrer.
- Controls: Reconstituted water (untreated test medium)
- Evidence of undissolved material: The test medium was a slightly yellowish preparation and stayed unchanged throughout the study.
Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:
TEST ORGANISM
- Common name: Zebrafish
- Strain: Tübinger Strain
- Source: Max-Planck-Institute, Tübingen, Germany
- Length at study initiation: 2.0 ± 1.0 cm
- Maintenance of the brood fish: Before the start of exposure, the fish were kept in a glass aquarium for at least 12 d in an air-conditioned laboratory at a water temperature of 21 - 25 °C and a 12 h light and 12 h dark regime to ensure similar conditions as in the experiment. Aerated reconstituted water was used as holding medium. The fish were fed daily with Tetra Min diet (Tetra GmbH, Melle, Germany) and frozen artemia. The fish were last fed 24 h before test start.

FEEDING DURING TEST
No feeding during the test.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Hardness:
223 mg CaCO3/L (reconstituted water)
Test temperature:
21.5 - 22.2 °C
pH:
0 h: 7.91 (control), 7.40 (treatment)
96 h: 7.48 (control), 7.54 (treatment)
Dissolved oxygen:
0 h: 95.6% O2 (control), 96.4% O2 (treatment)
96 h: 88.1% O2 (control), 87.9% O2 (treatment)
Conductivity:
676 µS/cm (reconstituted water)
Nominal and measured concentrations:
Control and 100 mg/L (nominal)
< LOD and 97.88 mg/L (0 h)/ 98.29 mg/L (96 h)
Details on test conditions:
TEST SYSTEM
- Test vessel: All-glass aquariums containing about 10 L test solution.
- Type: Open vessels, covered to allow air exchange.
- Aeration: No aeration during exposure
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: A maximum stocking density of 1 g fish per Liter medium was not exceeded.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water was prepared by dissolving the medium components in fully demineralized water (Milli-Q Water Purification System).
- Acid capacity: 0.8 mmol/L
- Ca/Mg ratio: 4:1
- Na/K ratio: 10:1
- Culture medium different from test medium: Culture medium same as test medium.
- Intervals of water quality measurement: 24 h

OTHER TEST CONDITIONS
- Adjustment of pH: The pH of the test solution was not adjusted.
- Photoperiod: 12 h light and 12 h dark

EFFECT PARAMETERS MEASURED:
- Mortality: 3 h after start of exposure and then daily.
- Clinical symptoms: 3 h after start of exposure and then daily (e.g. equilibrium, swimming behaviour, respiration, pigmentation, etc.).
- Length and Body Weight: At the end of exposure

TEST CONCENTRATIONS
- Range finding study: Yes
- Results used to determine the conditions for the definitive study: Yes. In a static pre-test no toxic effects were observed at 100 mg/L test item in open vessels. In a separate study the stability of the test item in reconstituted water for fish was confirmed over a period of 96 h in open vessels and after deep-freezing.
Reference substance (positive control):
not required
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
- Behavioural abnormalities: No clinical symptoms were observed.
- Observations on body length and weight: Length: 2.6 - 2.7 cm (control), 2.6 - 2.8 cm (treatment); Body Weight: 0.3 - 0.5 g (control), 0.4 - 0.6 g (treatment)
- Mortality of control: The mortality at the end of the study in the control did not exceed the 10% limit.

VALIDITY CRITERIA

 The test fulfilled the validity criteria of the OECD guideline 201 (Table 1).

 

Table 1: Validity criteria of OECD 201.

Criterion from the guideline

Study results

Validity criterion fulfilled

The mortality in the control(s) should not exceed 10% (or one fish if less than ten are used) at the end of the test

Mortality in the control was below 10% at the end of the study.

Yes

 

Validity criteria fulfilled:
yes
Remarks:
For further details please refer to “Any other information on results incl. tables”.

Description of key information

LC50 (96 h) > 100 mg/L (nominal, OECD 203, D. rerio); read-across

Key value for chemical safety assessment

Additional information

There is no study available, in which the short-term toxicity of the target substance 2-[3-[(4-Amino-2-methylpyrimidin-5-yl)methyl]-4-methyl-1,3-thiazoniol-5-yl]ethyl dihydrogen diphosphate (CAS 136-09-4) to fish was investigated. Therefore, read-across to the structurally and physico-chemically related source substance 2-{3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-4-methyl-1,3-thiazol-3-ium-5-yl}ethyl hydrogen phosphate (CAS 10023-48-0) was conducted in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5. Based on the high physico-chemical similarity, the source substance is considered a suitable proxy for the assessment of the short-term toxicity of the target substance to fish. A detailed analogue approach justification is provided in IUCLID section 13 of the technical dossier.

 

In the available study, the short-term toxicity of the source substance (CAS 10023-48-0) to fish was investigated according to OECD guideline 201 and GLP. In a static limit test, Danio rerio was exposed to a limit concentration of 100 mg/L test item in open test vessels for 96 h. Test item concentrations were analytically verified at the beginning (0 h) and end of the test (96 h) by HPLC-UV.

The measured test item concentrations were 97.9% and 98.3% of the nominal concentration at 0 h and 96 h, respectively, indicating that the substance was stable in reconstituted water for the duration of the test. Therefore, the actual concentrations were within ± 20% of the nominal concentration and the LC50 value was based on the nominal concentration.

After 96 h, neither acute toxicity nor clinical symptoms were observed at the nominal concentration of 100 mg/L. The reported LC50 (96 h) is > 100 mg/L (nominal).

Based on the high degree of structural and chemical similarity of the target and source substance, the target substance is expected to exhibit a similar ecotoxicological profile as the source substance. Therefore, it can be concluded that the target substance 2-[3-[(4-Amino-2-methylpyrimidin-5-yl)methyl]-4-methyl-1,3-thiazoniol-5-yl]ethyl dihydrogen diphosphate (CAS 136-09-4) does not cause short-term toxicity to fish up to a nominal concentration of 100 mg/L.